1. Field of the Invention
The present invention relates to a video signal processor for executing encoding and decoding processes of a video signal.
2. Description of the Related Art
Video recording reproduction devices, such as a hard disk drive (HDD) recorders and a digital versatile disk (DVD) recorders, encode an input signal, and decode an encoded video signal, in accordance with standards such as the moving picture expert group (MPEG) 2. The encoding and decoding are contrary procedures, but the encoding and decoding processes of the MPEG 2 can be executed by similar hardware arrangements. It is desirable that the encoding and decoding processes are executed utilizing a codec that operates in synchronization with a single synchronization signal.
The analog color television broadcasting standards used around the world are broken down into the following: the national television system committee (NTSC) standard, the phase alternation by line (PAL) standard, and the sequential color with memory (SECAM) standard. In the NTSC standard, 30 frames are broadcasted per second by dividing a frame into 525 lines. In the PAL and SECAM standards, 25 frames are broadcasted per second by dividing a frame into 625 lines.
As described above, the synchronization frequency of the NTSC standard is 30 [Hz], and the synchronization frequency of the PAL standard and the SECAM standard is 25 [Hz]. The PAL standard and the NTSC standard are sometimes used together because locales such as Europe and China adopt the PAL standard, while the video-content-rich United States of America employs the NTSC standard. A video signal processor capable of generating an output video signal having a synchronization frequency of the PAL standard by decoding an encoded video signal of the NTSC standard has been proposed to solve the problem.
However, when the encoding and decoding processes are executed by utilizing a codec that operates in synchronization with a synchronization signal, it is difficult to deal with video signals having different synchronization frequencies in executing the encoding and decoding processes. That is, it is impossible to execute a decoding process of an encoded video signal that conforms to the NTSC standard, and an encoding of an input video signal that conforms to the PAL or SECAM standard, at the same time. Although it is possible to deal with video signals having different synchronization frequencies by preparing both an encoder and a decoder which utilizes different synchronization signal, the hardware scale and power consumption of the video signal processor increases.